Nutrition Researchers Say It’s the Doctors Who Are Fooling Themselves – Are They?

“We have to be cautious not to use the n-of-1 experience or even the n-of-1000 experience in clinical practice as evidence itself, because that gets us back to the days of anecdotal clinical experience and we have learned that anecdotal clinical experience is… its the worst kind of observational epidemiology, right?”

Dariush Mozaffarian, then Dean of the Tufts University Friedman School of Nutrition Science and Policy, speaking on a panel, June 15, 2018 

I’ll bite. Should we really dismiss the observations of health practitioners working directly with their patients as the worst kind of observational epidemiology? Is it?

Before getting to an answer, here’s the context: Mozaffarian is among the most influential nutrition authorities in the world. He’s currently director of the Tufts Food as Medicine Institute and a key player trying to induce the federal government to create a National Institute of Nutrition.

The epigraph is a comment he made at a meeting in Zurich, Switzerland, hosted by the BMJ and Swiss Re, the world’s second-largest reinsurance company. ^[i]  The meeting was the first in a series of three so far – all called Food for Thought -- the purpose of which has been to bring together leading authorities from the nutrition research community with the academics, and the physicians and healthcare providers treating obesity and diabetes in their clinics, who have come to believe that the conventional thinking on prevention and therapy for those disorders is incorrect. That first meeting, which I helped organize, can be viewed as an attempt to understand why these two communities hold such antithetical perspectives and to consider the steps necessary to resolve the controversy.

We’re talking about it now, almost six years later, because a British physician named David Unwin recently evoked the meeting in an article published in the journal BMJ Nutrition, Prevention and Health (BMJ NPH). Unwin was at the meeting because he had an experience similar to many of the physicians and healthcare providers who attended.

Unwin had spent his career treating ever more obese and diabetic patients and had seen them only very rarely, if at all, benefit from the conventional diet and lifestyle advice he was giving. Then he changed his approach, motivated initially by the experience of a single patient. Here’s Unwin describing his experience in his BMJ NPH article:

From 1986 until 2012… I handed out `standard advice’ to my patients around weight loss. This included `eat less, move more’, `everything in moderation’ and advice around calorie counting as part of a low-fat diet. It was rarely effective. For 26 years I blamed my patients for their poor results. Like so many doctors in primary care I came to believe it was a poor use of my time giving dietary advice to help people lose weight. It never once occurred to me that my poor advice was the common denominator. This changed suddenly 11 years ago when an angry patient asked me why I had never discussed reducing dietary carbohydrates as a way to lose weight and improve blood sugar. Since then, learning from that patient and many others, our 9900-patient practice has been offering the option of a low carbohydrate diet, particularly to our patients with T2 diabetes and pre-diabetes. We have audited our clinical data and published the results in this journal. We recorded a mean weight loss of over 10% body weight at 3 years.

At the very end of the two-day Zurich meeting in 2018, Unwin asked Mozaffarian what clinicians like himself could do to improve the science around nutrition. After all, Unwin and his fellow physicians are the ones in the trenches who are obligated to give useful advice to their obese and diabetic patients; they’re the ones who see what works and what doesn’t and the consequences of both the successes and failures. So how can they be involved? In his article, Unwin paraphrased Mozaffarian’s response as “better to leave it to the scientists!”, which I think is a fair representation. You can listen to Unwin’s question here and Mozaffarian’s response and decide for yourself.  

The explanation that Mozaffarian offered for the implicit leave-it-to-the-scientists message was the quote I used in the epigraph: “We have to be cautious not to use the n-of-1 experience or even the n-of-1000 experience in clinical practice as evidence itself, because that gets us back to the days of anecdotal clinical experience and we have learned that anecdotal clinical experience is… its the worst kind of observational epidemiology, right?”

So… Is it?

To Mozaffarian’s credit, the question hits the nail of this conflict squarely on the head: the entire history of controversy surrounding dietary therapy for obesity and diabetes has been generated by physicians like Unwin suggesting they know better how to successfully treat their patients than the academics in their Ivy towers. In this history, the physicians have argued for the benefits of carbohydrate restriction, as Unwin does. They have based their belief, as Unwin does, on their n-of-1 to n-of-1000 cases, the very evidence that Mozaffarian rejects as inherently unreliable. Mozaffarian and his fellow authorities in the nutrition world argue that there’s nothing unique about carbohydrate restriction – that a calorie is more or less a calorie -- and believing anything else is delusional. And they base that belief on their interpretation of the evidence from the research that they do – clinical trials and epidemiologic surveys.

Somebody, of course, has to be wrong; someone is misinterpreting what they’re seeing.

Who do we believe? Who’s got the better perspective when it comes to treating patients with obesity and diabetes? Or, given that both doctors and epidemiologists like Mozaffarian are relying on their observations, are the n-of-1 to n-of-1000 cases treated by the physician, really the worst kind of observational epidemiology, or does that honor go to the kind of research being done by the academics?